The present invention relates to electrostatic precipitators and, more particularly, a method and apparatus for preventing wear of electrode holders on a discharge electrode frame of an electrostatic precipitator.
In an electrostatic precipitator, a gas laden with entrained particulate material is passed through an electrostatic field established about a discharge electrode disposed between two grounded collecting electrodes. The suspended particles become electrically charged as they pass through the electrostatic field and move under the influence of the electrostatic field to deposit upon the grounded collecting electrodes flanking the discharge electrode.
Typically, each collecting electrode is formed of one or more elongated plates disposed in a row side-by-side and suspended from the top of a precipitator housing in a vertical plane. A plurality of such collecting electrodes are disposed transversely across the precipitator casing in spaced vertical planes parallel to the direction of the gas flow through the precipitator.
In what is commonly referred to as a rigid-frame electrostatic precipitator, a box-like framework comprised of a plurality of discharge electrode frames is suspended from insulators at the top of the precipitator housing. Each discharge electrode frame supports a plurality of vertically disposed discharge electrodes between adjacent collecting electrodes. The discharge electrodes are typically wires, bands, or the like, which are toughly strung across the discharge electrode frame and connected to the electrode frame at features on the electrode frame called electrode connectors. A voltage is applied to the discharge electrodes via the electrode frame to generate the electrostatic field.
During operation, some dust particles will deposit on the discharge electrodes rather than migrating to the collecting electrode plates. Therefore, it may be necessary to occasionally clean the discharge electrodes by vibrating the discharge electrode frames, typically by means of a rapping mechanism. Over time, this vibrating action as well as movement of the electrodes due to flue gas velocity and arcing between the electrode 36 and electrode holder tend to wear the end portions of the discharge electrodes and the electrode holders. Because of this wear, maintenance personnel will typically replace the discharge electrodes one or more times over the life of the electrostatic precipitator. The electrode holders are typically not replaced because this would require time-consuming disassembly of much of the electrostatic precipitator, grinding removal of the worn electrode holders, and welding attachment of the new electrode holders. Problematically, however, the worn discharge electrode holders provide uneven surfaces on which the new discharge electrodes are installed, which can cause premature wear of the new discharge electrodes.